DETROIT – Going on sale in midyear, the Tribute Hybrid to be unveiled tomorrow at the North American International Auto Show is Mazda North American Operations’ first hybrid-electric vehicle.

The small cross/utility HEV joins siblings, the Ford Escape Hybrid and Mercury Mariner Hybrid, which have been on sale for more than a year.

Mazda says the Tribute is a full hybrid, able to run 100% on its electric power up to approximately 25 mph (40 km/h).

“The Tribute HEV is the next step towards strengthening Mazda’s environmental efforts,” Robert Davis, senior vice president-quality, research and development, says.

Mazda currently is testing hydrogen-powered versions of the RX-8 sports car and Mazda5 multipurpose vehicle in Japan.

The Tribute HEV is powered by a 2.3L 4-cyl. Atkinson-cycle engine making 133 hp at 6,000 rpm and 124 lb.-ft. (168 Nm) of torque at 4,250 rpm.

The electric traction motor adds another 94 hp (70 kW) at 5,000 rpm.

Combined output is 155 hp.

Mazda says the HEV has a 0-60 mph (97 km/h) time comparable to a 200-hp, V-6 equipped vehicle. However, city-driving fuel economy is improved about 75% compared with the Tribute’s gasoline version.

The Tribute HEV has a 330-volt nickel-metal-hydride battery pack in the vehicle’s rear load floor, and an electronically controlled, continuously variable transmission is mated to the engine.

The electronic vehicle system controller kills the engine when the vehicle is stopped or coasting, while also managing engine starts and charging, Mazda says.

A charge/assist gauge on the dashboard lets the driver know when the vehicle is cycling through its four modes: all-electric, gas-electric, gas-only and battery-charging. Otherwise, Mazda says the transition between the modes is seamless and not detectable.

The Tribute HEV is available in standard front-wheel drive or optional electronic 4-wheel-drive configurations.

Two trims, Touring and Grand Touring, will be offered.

Tribute models for ’08 have new front and rear fascias, as well as an updated hood, liftgate, body-side molding, power side-view mirrors, headlamps, taillamps and standard fog lights.

Standard safety features include advanced front airbags with sensors, seat-mounted side airbags, front side-impact airbags and side-impact air curtains. Antilock brakes also are standard, as is a tire pressure monitoring system.

Pricing and fuel economy ratings will be announced closer to the Tribute Hybrid’s on-sale date, Mazda says.

“We’re probably going to (offer the new HEV on a) very limited (basis) to begin with,” Jim O’Sullivan, president and CEO of Mazda in North America, told Ward’s last November. “We’ll see how the market reaction is.”